tarfile — Read and write tar archive files读取和写入tar存档文件

Source code: Lib/tarfile.py

The tarfile module makes it possible to read and write tar archives, including those using gzip, bz2 and lzma compression. tarfile模块可以读取和写入tar档案，包括使用gzip、bz2和lzma压缩的档案。Use the zipfile module to read or write .zip files, or the higher-level functions in shutil.使用zipfile模块读取或写入.zip文件，或使用shutil中的高级函数。

Some facts and figures:一些事实和数字：

  • reads and writes gzip, bz2 and lzma compressed archives if the respective modules are available.读取和写入gzip、bz2和lzma压缩档案（如果相应模块可用）。

  • read/write support for the POSIX.1-1988 (ustar) format.对POSIX的读/写支持。1-1988(ustar)格式。

  • read/write support for the GNU tar format including longname and longlink extensions, read-only support for all variants of the sparse extension including restoration of sparse files.对GNU tar格式的读/写支持，包括longname和longlink扩展，对稀疏扩展的所有变体的只读支持，包括稀疏文件的恢复。

  • read/write support for the POSIX.1-2001 (pax) format.对POSIX的读/写支持。1-2001(pax)格式。

  • handles directories, regular files, hardlinks, symbolic links, fifos, character devices and block devices and is able to acquire and restore file information like timestamp, access permissions and owner.处理目录、常规文件、硬链接、符号链接、FIFO、字符设备和块设备，并能够获取和恢复文件信息，如时间戳、访问权限和所有者。

Changed in version 3.3:版本3.3中更改： Added support for lzma compression.增加了对lzma压缩的支持。

tarfile.open(name=None, mode='r', fileobj=None, bufsize=10240, **kwargs)

Return a TarFile object for the pathname name. 返回路径名name的TarFile对象。For detailed information on TarFile objects and the keyword arguments that are allowed, see TarFile Objects.有关TarFile对象和允许的关键字参数的详细信息，请参阅TarFile对象。

mode has to be a string of the form 'filemode[:compression]', it defaults to 'r'. mode必须是格式为'filemode[:compression]'的字符串，默认为'r'。Here is a full list of mode combinations:以下是模式组合的完整列表：

mode模式

action操作

'r' or 'r:*'

Open for reading with transparent compression (recommended).使用透明压缩打开阅读（推荐）。

'r:'

Open for reading exclusively without compression.无需压缩即可完全阅读。

'r:gz'

Open for reading with gzip compression.用gzip压缩打开阅读。

'r:bz2'

Open for reading with bzip2 compression.使用bzip2压缩打开阅读。

'r:xz'

Open for reading with lzma compression.使用lzma压缩打开阅读。

'x' or 'x:'

Create a tarfile exclusively without compression. 以独占方式创建TAR文件，无需压缩。Raise an FileExistsError exception if it already exists.如果FileExistsError异常已经存在，则引发该异常。

'x:gz'

Create a tarfile with gzip compression. 使用gzip压缩创建tarfile。Raise an FileExistsError exception if it already exists.如果FileExistsError异常已经存在，则引发该异常。

'x:bz2'

Create a tarfile with bzip2 compression. 使用bzip2压缩创建tarfile。Raise an FileExistsError exception if it already exists.如果FileExistsError异常已经存在，则引发该异常。

'x:xz'

Create a tarfile with lzma compression. 使用lzma压缩创建tarfile。Raise an FileExistsError exception if it already exists.如果FileExistsError异常已经存在，则引发该异常。

'a' or 'a:'

Open for appending with no compression. 打开以进行附加，无需压缩。The file is created if it does not exist.如果文件不存在，则创建该文件。

'w' or 'w:'

Open for uncompressed writing.打开以进行未压缩写作。

'w:gz'

Open for gzip compressed writing.打开gzip压缩写入。

'w:bz2'

Open for bzip2 compressed writing.打开bzip2压缩写入。

'w:xz'

Open for lzma compressed writing.打开lzma压缩写入。

Note that 'a:gz', 'a:bz2' or 'a:xz' is not possible. 请注意，'a:gz'、'a:bz2'或'a:xz'是不可能的。If mode is not suitable to open a certain (compressed) file for reading, ReadError is raised. 如果mode不适合打开某个（压缩）文件进行读取，则会引发ReadError。Use mode 'r' to avoid this. 使用mode'r'可以避免这种情况。If a compression method is not supported, CompressionError is raised.如果不支持压缩方法，则会引发CompressionError。

If fileobj is specified, it is used as an alternative to a file object opened in binary mode for name. 如果指定了fileobj，它将用作以二进制模式打开的文件对象的替代名称。It is supposed to be at position 0.它应该位于位置0。

For modes 'w:gz', 'r:gz', 'w:bz2', 'r:bz2', 'x:gz', 'x:bz2', tarfile.open() accepts the keyword argument compresslevel (default 9) to specify the compression level of the file.对于模式'w:gz'、'r:gz'、'w:bz2'、'r:bz2'、'x:gz'、'x:bz2'，tarfile.open()接受关键字参数compresslevel（默认值9）来指定文件的压缩级别。

For modes 'w:xz' and 'x:xz', tarfile.open() accepts the keyword argument preset to specify the compression level of the file.

For special purposes, there is a second format for mode: 'filemode|[compression]'. tarfile.open() will return a TarFile object that processes its data as a stream of blocks. No random seeking will be done on the file. If given, fileobj may be any object that has a read() or write() method (depending on the mode). bufsize specifies the blocksize and defaults to 20 * 512 bytes. Use this variant in combination with e.g. sys.stdin, a socket file object or a tape device. However, such a TarFile object is limited in that it does not allow random access, see Examples. The currently possible modes:当前可能的模式：

Mode模式

Action操作

'r|*'

Open a stream of tar blocks for reading with transparent compression.打开一个tar块stream，通过透明压缩进行读取。

'r|'

Open a stream of uncompressed tar blocks for reading.打开未压缩的tar块stream进行读取。

'r|gz'

Open a gzip compressed stream for reading.

'r|bz2'

Open a bzip2 compressed stream for reading.

'r|xz'

Open an lzma compressed stream for reading.

'w|'

Open an uncompressed stream for writing.

'w|gz'

Open a gzip compressed stream for writing.

'w|bz2'

Open a bzip2 compressed stream for writing.

'w|xz'

Open an lzma compressed stream for writing.

Changed in version 3.5:版本3.5中更改： The 'x' (exclusive creation) mode was added.

Changed in version 3.6:版本3.6中更改： The name parameter accepts a path-like object.

classtarfile.TarFile

Class for reading and writing tar archives. 阅读和写作tar档案的课程。Do not use this class directly: use tarfile.open() instead. 不要直接使用此类：请改用tarfile.open()。See TarFile Objects.请参见TarFile对象。

tarfile.is_tarfile(name)

Return True if name is a tar archive file, that the tarfile module can read. name may be a str, file, or file-like object.

Changed in version 3.9:版本3.9中更改： Support for file and file-like objects.支持文件和类似文件的对象。

The tarfile module defines the following exceptions:tarfile模块定义了以下异常：

exceptiontarfile.TarError

Base class for all tarfile exceptions.

exceptiontarfile.ReadError

Is raised when a tar archive is opened, that either cannot be handled by the tarfile module or is somehow invalid.在打开tar归档文件时引发，该文件无法由tarfile模块处理或以某种方式无效。

exceptiontarfile.CompressionError

Is raised when a compression method is not supported or when the data cannot be decoded properly.在不支持压缩方法或数据无法正确解码时引发。

exceptiontarfile.StreamError

Is raised for the limitations that are typical for stream-like TarFile objects.针对类流TarFile对象的典型限制而提出。

exceptiontarfile.ExtractError

Is raised for non-fatal errors when using TarFile.extract(), but only if TarFile.errorlevel== 2.在使用TarFile.extract()时，仅当TarFile.errorlevel== 2时，才会针对非致命错误引发。

exceptiontarfile.HeaderError

Is raised by TarInfo.frombuf() if the buffer it gets is invalid.如果获取的缓冲区无效，则由TarInfo.frombuf()引发。

The following constants are available at the module level:以下常数在模块级可用：

tarfile.ENCODING

The default character encoding: 'utf-8' on Windows, the value returned by sys.getfilesystemencoding() otherwise.默认字符编码：在Windows上为'utf-8'，否则为sys.getfilesystemencoding()返回的值。

Each of the following constants defines a tar archive format that the tarfile module is able to create. 以下每个常量都定义了tarfile模块能够创建的tar归档格式。See section Supported tar formats for details.有关详细信息，请参阅支持的tar格式一节。

tarfile.USTAR_FORMAT

POSIX.1-1988 (ustar) format.格式。

tarfile.GNU_FORMAT

GNU tar format.GNU tar格式。

tarfile.PAX_FORMAT

POSIX.1-2001 (pax) format.

tarfile.DEFAULT_FORMAT

The default format for creating archives. 创建存档的默认格式。This is currently PAX_FORMAT.这目前是PAX_FORMAT。

Changed in version 3.8:版本3.8中更改： The default format for new archives was changed to PAX_FORMAT from GNU_FORMAT.

See also另请参见

Module zipfile

Documentation of the zipfile standard module.zipfile标准模块的文档。

Archiving operations归档操作

Documentation of the higher-level archiving facilities provided by the standard shutil module.标准shutil模块提供的高级归档设施的文档。

GNU tar manual, Basic Tar FormatGNU tar手册，基本tar格式

Documentation for tar archive files, including GNU tar extensions.tar归档文件的文档，包括GNU tar扩展。

TarFile Objects对象

The TarFile object provides an interface to a tar archive. TarFile对象提供了到tar存档的接口。A tar archive is a sequence of blocks. tar归档是一系列块。An archive member (a stored file) is made up of a header block followed by data blocks. 存档成员（存储的文件）由头块和数据块组成。It is possible to store a file in a tar archive several times. 可以将文件多次存储在tar归档中。Each archive member is represented by a TarInfo object, see TarInfo Objects for details.每个存档成员由一个TarInfo对象表示，有关详细信息，请参阅TarInfo对象。

A TarFile object can be used as a context manager in a with statement. It will automatically be closed when the block is completed. 当区块完成时，它将自动关闭。Please note that in the event of an exception an archive opened for writing will not be finalized; only the internally used file object will be closed. 请注意，如果出现例外情况，则不会最终确定为写作而打开的档案；仅关闭内部使用的文件对象。See the Examples section for a use case.有关用例，请参阅示例部分。

New in version 3.2.版本3.2中新增。Added support for the context management protocol.添加了对上下文管理协议的支持。

classtarfile.TarFile(name=None, mode='r', fileobj=None, format=DEFAULT_FORMAT, tarinfo=TarInfo, dereference=False, ignore_zeros=False, encoding=ENCODING, errors='surrogateescape', pax_headers=None, debug=0, errorlevel=0)

All following arguments are optional and can be accessed as instance attributes as well.以下所有参数都是可选的，也可以作为实例属性访问。

name is the pathname of the archive. name may be a path-like object. It can be omitted if fileobj is given. In this case, the file object’s name attribute is used if it exists.

mode is either 'r' to read from an existing archive, 'a' to append data to an existing file, 'w' to create a new file overwriting an existing one, or 'x' to create a new file only if it does not already exist.

If fileobj is given, it is used for reading or writing data. If it can be determined, mode is overridden by fileobj’s mode. fileobj will be used from position 0.

Note

fileobj is not closed, when TarFile is closed.

format controls the archive format for writing. It must be one of the constants USTAR_FORMAT, GNU_FORMAT or PAX_FORMAT that are defined at module level. When reading, format will be automatically detected, even if different formats are present in a single archive.

The tarinfo argument can be used to replace the default TarInfo class with a different one.

If dereference is False, add symbolic and hard links to the archive. If it is True, add the content of the target files to the archive. This has no effect on systems that do not support symbolic links.

If ignore_zeros is False, treat an empty block as the end of the archive. If it is True, skip empty (and invalid) blocks and try to get as many members as possible. This is only useful for reading concatenated or damaged archives.

debug can be set from 0 (no debug messages) up to 3 (all debug messages). The messages are written to sys.stderr.

If errorlevel is 0, all errors are ignored when using TarFile.extract(). Nevertheless, they appear as error messages in the debug output, when debugging is enabled. If 1, all fatal errors are raised as OSError exceptions. If 2, all non-fatal errors are raised as TarError exceptions as well.

The encoding and errors arguments define the character encoding to be used for reading or writing the archive and how conversion errors are going to be handled. The default settings will work for most users. See section Unicode issues for in-depth information.

The pax_headers argument is an optional dictionary of strings which will be added as a pax global header if format is PAX_FORMAT.

Changed in version 3.2:版本3.2中更改： Use 'surrogateescape' as the default for the errors argument.

Changed in version 3.5:版本3.5中更改： The 'x' (exclusive creation) mode was added.添加了'x'（独占创建）模式。

Changed in version 3.6:版本3.6中更改： The name parameter accepts a path-like object.

classmethodTarFile.open(...)

Alternative constructor. 替代构造函数。The tarfile.open() function is actually a shortcut to this classmethod.tarfile.open()函数实际上是这个类方法的快捷方式。

TarFile.getmember(name)

Return a TarInfo object for member name. 返回成员name的TarInfo对象。If name can not be found in the archive, KeyError is raised.如果在存档中找不到name，则会引发KeyError。

Note

If a member occurs more than once in the archive, its last occurrence is assumed to be the most up-to-date version.如果一个成员在存档中出现多次，则认为其最后一次出现是最新版本。

TarFile.getmembers()

Return the members of the archive as a list of TarInfo objects. 以TarInfo对象列表的形式返回存档的成员。The list has the same order as the members in the archive.列表的顺序与存档中的成员相同。

TarFile.getnames()

Return the members as a list of their names. 将成员作为其姓名列表返回。It has the same order as the list returned by getmembers().它的顺序与getmembers()返回的列表相同。

TarFile.list(verbose=True, *, members=None)

Print a table of contents to sys.stdout. If verbose is False, only the names of the members are printed. If it is True, output similar to that of ls -l is produced. If optional members is given, it must be a subset of the list returned by getmembers().

Changed in version 3.5:版本3.5中更改： Added the members parameter.添加了members参数。

TarFile.next()

Return the next member of the archive as a TarInfo object, when TarFile is opened for reading. Return None if there is no more available.

TarFile.extractall(path='.', members=None, *, numeric_owner=False)

Extract all members from the archive to the current working directory or directory path. If optional members is given, it must be a subset of the list returned by getmembers(). Directory information like owner, modification time and permissions are set after all members have been extracted. This is done to work around two problems: A directory’s modification time is reset each time a file is created in it. And, if a directory’s permissions do not allow writing, extracting files to it will fail.

If numeric_owner is True, the uid and gid numbers from the tarfile are used to set the owner/group for the extracted files. Otherwise, the named values from the tarfile are used.

Warning

Never extract archives from untrusted sources without prior inspection. 未经事先检查，不得从不受信任的来源提取档案。It is possible that files are created outside of path, e.g. members that have absolute filenames starting with "/" or filenames with two dots "..".

Changed in version 3.5:版本3.5中更改： Added the numeric_owner parameter.

Changed in version 3.6:版本3.6中更改： The path parameter accepts a path-like object.

TarFile.extract(member, path='', set_attrs=True, *, numeric_owner=False)

Extract a member from the archive to the current working directory, using its full name. Its file information is extracted as accurately as possible. member may be a filename or a TarInfo object. You can specify a different directory using path. path may be a path-like object. File attributes (owner, mtime, mode) are set unless set_attrs is false.

If numeric_owner is True, the uid and gid numbers from the tarfile are used to set the owner/group for the extracted files. Otherwise, the named values from the tarfile are used.

Note

The extract() method does not take care of several extraction issues. In most cases you should consider using the extractall() method.

Warning

See the warning for extractall().

Changed in version 3.2:版本3.2中更改： Added the set_attrs parameter.

Changed in version 3.5:版本3.5中更改： Added the numeric_owner parameter.

Changed in version 3.6:版本3.6中更改： The path parameter accepts a path-like object.

TarFile.extractfile(member)

Extract a member from the archive as a file object. member may be a filename or a TarInfo object. If member is a regular file or a link, an io.BufferedReader object is returned. For all other existing members, None is returned. If member does not appear in the archive, KeyError is raised.

Changed in version 3.3:版本3.3中更改： Return an io.BufferedReader object.

TarFile.add(name, arcname=None, recursive=True, *, filter=None)

Add the file name to the archive. name may be any type of file (directory, fifo, symbolic link, etc.). If given, arcname specifies an alternative name for the file in the archive. Directories are added recursively by default. This can be avoided by setting recursive to False. Recursion adds entries in sorted order. If filter is given, it should be a function that takes a TarInfo object argument and returns the changed TarInfo object. If it instead returns None the TarInfo object will be excluded from the archive. See Examples for an example.

Changed in version 3.2:版本3.2中更改： Added the filter parameter.

Changed in version 3.7:版本3.7中更改： Recursion adds entries in sorted order.

TarFile.addfile(tarinfo, fileobj=None)

Add the TarInfo object tarinfo to the archive. If fileobj is given, it should be a binary file, and tarinfo.size bytes are read from it and added to the archive. You can create TarInfo objects directly, or by using gettarinfo().

TarFile.gettarinfo(name=None, arcname=None, fileobj=None)

Create a TarInfo object from the result of os.stat() or equivalent on an existing file. The file is either named by name, or specified as a file object fileobj with a file descriptor. name may be a path-like object. If given, arcname specifies an alternative name for the file in the archive, otherwise, the name is taken from fileobj’s name attribute, or the name argument. The name should be a text string.

You can modify some of the TarInfo’s attributes before you add it using addfile(). If the file object is not an ordinary file object positioned at the beginning of the file, attributes such as size may need modifying. This is the case for objects such as GzipFile. The name may also be modified, in which case arcname could be a dummy string.

Changed in version 3.6:版本3.6中更改： The name parameter accepts a path-like object.

TarFile.close()

Close the TarFile. In write mode, two finishing zero blocks are appended to the archive.

TarFile.pax_headers

A dictionary containing key-value pairs of pax global headers.包含pax全局头的键值对的字典。

TarInfo Objects对象

A TarInfo object represents one member in a TarFile. Aside from storing all required attributes of a file (like file type, size, time, permissions, owner etc.), it provides some useful methods to determine its type. It does not contain the file’s data itself.它不包含文件本身的数据。

TarInfo objects are returned by TarFile’s methods getmember(), getmembers() and gettarinfo().

classtarfile.TarInfo(name='')

Create a TarInfo object.创建TarInfo对象。

classmethodTarInfo.frombuf(buf, encoding, errors)

Create and return a TarInfo object from string buffer buf.

Raises HeaderError if the buffer is invalid.如果缓冲区无效，则引发HeaderError。

classmethodTarInfo.fromtarfile(tarfile)

Read the next member from the TarFile object tarfile and return it as a TarInfo object.

TarInfo.tobuf(format=DEFAULT_FORMAT, encoding=ENCODING, errors='surrogateescape')

Create a string buffer from a TarInfo object. For information on the arguments see the constructor of the TarFile class.

Changed in version 3.2:版本3.2中更改： Use 'surrogateescape' as the default for the errors argument.

A TarInfo object has the following public data attributes:

TarInfo.name

Name of the archive member.

TarInfo.size

Size in bytes.

TarInfo.mtime

Time of last modification.

TarInfo.mode

Permission bits.

TarInfo.type

File type. type is usually one of these constants: REGTYPE, AREGTYPE, LNKTYPE, SYMTYPE, DIRTYPE, FIFOTYPE, CONTTYPE, CHRTYPE, BLKTYPE, GNUTYPE_SPARSE. To determine the type of a TarInfo object more conveniently, use the is*() methods below.

TarInfo.linkname

Name of the target file name, which is only present in TarInfo objects of type LNKTYPE and SYMTYPE.

TarInfo.uid

User ID of the user who originally stored this member.

TarInfo.gid

Group ID of the user who originally stored this member.

TarInfo.uname

User name.

TarInfo.gname

Group name.

TarInfo.pax_headers

A dictionary containing key-value pairs of an associated pax extended header.

A TarInfo object also provides some convenient query methods:

TarInfo.isfile()

Return True if the Tarinfo object is a regular file.

TarInfo.isreg()

Same as isfile().

TarInfo.isdir()

Return True if it is a directory.

TarInfo.issym()

Return True if it is a symbolic link.

TarInfo.islnk()

Return True if it is a hard link.

TarInfo.ischr()

Return True if it is a character device.

TarInfo.isblk()

Return True if it is a block device.

TarInfo.isfifo()

Return True if it is a FIFO.

TarInfo.isdev()

Return True if it is one of character device, block device or FIFO.

Command-Line Interface

New in version 3.4.版本3.4中新增。

The tarfile module provides a simple command-line interface to interact with tar archives.

If you want to create a new tar archive, specify its name after the -c option and then list the filename(s) that should be included:

$ python -m tarfile -c monty.tar  spam.txt eggs.txt

Passing a directory is also acceptable:

$ python -m tarfile -c monty.tar life-of-brian_1979/

If you want to extract a tar archive into the current directory, use the -e option:

$ python -m tarfile -e monty.tar

You can also extract a tar archive into a different directory by passing the directory’s name:

$ python -m tarfile -e monty.tar  other-dir/

For a list of the files in a tar archive, use the -l option:

$ python -m tarfile -l monty.tar

Command-line options

-l <tarfile>
--list <tarfile>

List files in a tarfile.

-c <tarfile> <source1> ... <sourceN>
--create <tarfile> <source1> ... <sourceN>

Create tarfile from source files.

-e <tarfile> [<output_dir>]
--extract <tarfile> [<output_dir>]

Extract tarfile into the current directory if output_dir is not specified.

-t <tarfile>
--test <tarfile>

Test whether the tarfile is valid or not.

-v,--verbose

Verbose output.

Examples

How to extract an entire tar archive to the current working directory:

import tarfile
tar = tarfile.open("sample.tar.gz")
tar.extractall()
tar.close()

How to extract a subset of a tar archive with TarFile.extractall() using a generator function instead of a list:

import os
import tarfile
def py_files(members):
    for tarinfo in members:
        if os.path.splitext(tarinfo.name)[1] == ".py":
            yield tarinfo

tar = tarfile.open("sample.tar.gz")
tar.extractall(members=py_files(tar))
tar.close()

How to create an uncompressed tar archive from a list of filenames:

import tarfile
tar = tarfile.open("sample.tar", "w")
for name in ["foo", "bar", "quux"]:
    tar.add(name)
tar.close()

The same example using the with statement:

import tarfile
with tarfile.open("sample.tar", "w") as tar:
    for name in ["foo", "bar", "quux"]:
        tar.add(name)

How to read a gzip compressed tar archive and display some member information:

import tarfile
tar = tarfile.open("sample.tar.gz", "r:gz")
for tarinfo in tar:
    print(tarinfo.name, "is", tarinfo.size, "bytes in size and is ", end="")
    if tarinfo.isreg():
        print("a regular file.")
    elif tarinfo.isdir():
        print("a directory.")
    else:
        print("something else.")
tar.close()

How to create an archive and reset the user information using the filter parameter in TarFile.add():

import tarfile
def reset(tarinfo):
    tarinfo.uid = tarinfo.gid = 0
    tarinfo.uname = tarinfo.gname = "root"
    return tarinfo
tar = tarfile.open("sample.tar.gz", "w:gz")
tar.add("foo", filter=reset)
tar.close()

Supported tar formats

There are three tar formats that can be created with the tarfile module:

  • The POSIX.1-1988 ustar format (USTAR_FORMAT). It supports filenames up to a length of at best 256 characters and linknames up to 100 characters. The maximum file size is 8 GiB. This is an old and limited but widely supported format.

  • The GNU tar format (GNU_FORMAT). It supports long filenames and linknames, files bigger than 8 GiB and sparse files. It is the de facto standard on GNU/Linux systems. tarfile fully supports the GNU tar extensions for long names, sparse file support is read-only.

  • The POSIX.1-2001 pax format (PAX_FORMAT). It is the most flexible format with virtually no limits. It supports long filenames and linknames, large files and stores pathnames in a portable way. Modern tar implementations, including GNU tar, bsdtar/libarchive and star, fully support extended pax features; some old or unmaintained libraries may not, but should treat pax archives as if they were in the universally-supported ustar format. It is the current default format for new archives.

    It extends the existing ustar format with extra headers for information that cannot be stored otherwise. There are two flavours of pax headers: Extended headers only affect the subsequent file header, global headers are valid for the complete archive and affect all following files. All the data in a pax header is encoded in UTF-8 for portability reasons.

There are some more variants of the tar format which can be read, but not created:

  • The ancient V7 format. This is the first tar format from Unix Seventh Edition, storing only regular files and directories. Names must not be longer than 100 characters, there is no user/group name information. Some archives have miscalculated header checksums in case of fields with non-ASCII characters.

  • The SunOS tar extended format. This format is a variant of the POSIX.1-2001 pax format, but is not compatible.

Unicode issues

The tar format was originally conceived to make backups on tape drives with the main focus on preserving file system information. Nowadays tar archives are commonly used for file distribution and exchanging archives over networks. One problem of the original format (which is the basis of all other formats) is that there is no concept of supporting different character encodings. For example, an ordinary tar archive created on a UTF-8 system cannot be read correctly on a Latin-1 system if it contains non-ASCII characters. Textual metadata (like filenames, linknames, user/group names) will appear damaged. Unfortunately, there is no way to autodetect the encoding of an archive. The pax format was designed to solve this problem. It stores non-ASCII metadata using the universal character encoding UTF-8.

The details of character conversion in tarfile are controlled by the encoding and errors keyword arguments of the TarFile class.

encoding defines the character encoding to use for the metadata in the archive. The default value is sys.getfilesystemencoding() or 'ascii' as a fallback. Depending on whether the archive is read or written, the metadata must be either decoded or encoded. If encoding is not set appropriately, this conversion may fail.

The errors argument defines how characters are treated that cannot be converted. Possible values are listed in section Error Handlers. The default scheme is 'surrogateescape' which Python also uses for its file system calls, see File Names, Command Line Arguments, and Environment Variables.

For PAX_FORMAT archives (the default), encoding is generally not needed because all the metadata is stored using UTF-8. encoding is only used in the rare cases when binary pax headers are decoded or when strings with surrogate characters are stored.